Security keys are generally used in a radio communications network to authenticate users or devices and to encrypt data communicated in the network. This prevents one user or device masquerading as another user or device. It also prevents eavesdropping on communications in the network. A security key is a data string that is secret i.e., not generally known to users of the network.
Typically a control device manages the security keys of a network. When a new device attempts to join the network, the user of the control device tells the user of the new device a secret. e.g. a PIN. The user of the control device manually inputs the secret PIN to the control device and the user of the new device manually inputs the same secret PIN to the new device. The control device and the new device separately and symmetrically create a secret security key. This security key is necessary for authentication of the new device and/or encryption of communications between the devices.
When another new device attempts to join the network, the same process occurs except a different PIN is generally used.
Such security measures are, for example, used in a Bluetooth® piconet. The control device is a low power radio frequency transceiver device operating as a Master. The new device is a low power radio frequency transceiver device attempting to join the piconet as a Slave. The security key is an initialization key Kinit created during the Link Manager Protocol (LMP) pairing process. In Bluetooth, encryption and authentication use different keys and the initialisation key Kinit is used to ensure that a common link key, used in the authentication process, is shared by the Master device and the new Slave device.
It will therefore be appreciated to be disadvantageous that a user of the control device must enter data every time a new device attempts to join the network.
The inventors have realised that the user of the control device, if occupied in some other activity, must interrupt that activity to inform the new user of a new secret and enter the new secret to the device. This is particularly disadvantageous if the activity requires real time input such as a game.